Eric Meadows-Jonsson
d454aaf155
Fix Stream.take_while looping infinitely when given lazy stream. Fix Stream.take and Stream.take_while calling fun one extra time. Add more tests where Stream functions are given streams.
143 lines
3.9 KiB
Elixir
143 lines
3.9 KiB
Elixir
Code.require_file "test_helper.exs", __DIR__
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defmodule StreamTest do
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use ExUnit.Case, async: true
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test "streams as enumerables" do
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stream = Stream.map([1,2,3], &1 * 2)
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# Reduce
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assert Enum.map(stream, &1 + 1) == [3,5,7]
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# Member
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assert Enum.member?(stream, 4)
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refute Enum.member?(stream, 1)
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# Count
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assert Enum.count(stream) == 3
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end
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test "streams are composable" do
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stream = Stream.map([1,2,3], &1 * 2)
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assert is_lazy(stream)
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stream = Stream.map(stream, &1 + 1)
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assert is_lazy(stream)
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assert Enum.to_list(stream) == [3,5,7]
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end
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test :cycle do
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stream = Stream.cycle([1,2,3])
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assert is_function(stream)
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assert Stream.cycle([1,2,3]) |> Stream.take(5) |> Enum.to_list == [1,2,3,1,2]
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assert Enum.take(stream, 5) == [1,2,3,1,2]
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end
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test :drop do
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stream = Stream.drop(1..10, 5)
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assert is_lazy(stream)
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assert Enum.to_list(stream) == [6,7,8,9,10]
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assert Enum.to_list(Stream.drop(1..5, 0)) == [1,2,3,4,5]
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assert Enum.to_list(Stream.drop(1..3, 5)) == []
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nats = Stream.iterate(1, &(&1 + 1))
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assert Stream.drop(nats, 2) |> Enum.take(5) == [3,4,5,6,7]
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end
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test :drop_while do
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stream = Stream.drop_while(1..10, &1 <= 5)
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assert is_lazy(stream)
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assert Enum.to_list(stream) == [6,7,8,9,10]
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assert Enum.to_list(Stream.drop_while(1..5, &1 <= 0)) == [1,2,3,4,5]
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assert Enum.to_list(Stream.drop_while(1..3, &1 <= 5)) == []
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nats = Stream.iterate(1, &(&1 + 1))
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assert Stream.drop_while(nats, &1 <= 5) |> Enum.take(5) == [6,7,8,9,10]
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end
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test :filter do
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stream = Stream.filter([1,2,3], fn(x) -> rem(x, 2) == 0 end)
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assert is_lazy(stream)
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assert Enum.to_list(stream) == [2]
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nats = Stream.iterate(1, &(&1 + 1))
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assert Stream.filter(nats, &(rem(&1, 2) == 0)) |> Enum.take(5) == [2,4,6,8,10]
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end
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test :iterate do
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stream = Stream.iterate(0, &1+2)
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assert Enum.take(stream, 5) == [0,2,4,6,8]
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stream = Stream.iterate(5, &1+2)
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assert Enum.take(stream, 5) == [5,7,9,11,13]
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# Only calculate values if needed
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stream = Stream.iterate("HELLO", raise(&1))
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assert Enum.take(stream, 1) == ["HELLO"]
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end
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test :map do
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stream = Stream.map([1,2,3], &1 * 2)
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assert is_lazy(stream)
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assert Enum.to_list(stream) == [2,4,6]
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nats = Stream.iterate(1, &(&1 + 1))
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assert Stream.map(nats, &(&1 * 2)) |> Enum.take(5) == [2,4,6,8,10]
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end
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test :reject do
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stream = Stream.reject([1,2,3], fn(x) -> rem(x, 2) == 0 end)
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assert is_lazy(stream)
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assert Enum.to_list(stream) == [1,3]
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nats = Stream.iterate(1, &(&1 + 1))
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assert Stream.reject(nats, &(rem(&1, 2) == 0)) |> Enum.take(5) == [1,3,5,7,9]
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end
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test :repeatedly do
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stream = Stream.repeatedly(fn -> 1 end)
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assert Enum.take(stream, 5) == [1,1,1,1,1]
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stream = Stream.repeatedly(&:random.uniform/0)
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[r1,r2] = Enum.take(stream, 2)
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assert r1 != r2
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end
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test :take do
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stream = Stream.take(1..1000, 5)
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assert is_lazy(stream)
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assert Enum.to_list(stream) == [1,2,3,4,5]
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assert Enum.to_list(Stream.take(1..1000, 0)) == []
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assert Enum.to_list(Stream.take(1..3, 5)) == [1,2,3]
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nats = Stream.iterate(1, &(&1 + 1))
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assert Enum.to_list(Stream.take(nats, 5)) == [1,2,3,4,5]
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end
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test :take_while do
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stream = Stream.take_while(1..1000, &1 <= 5)
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assert is_lazy(stream)
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assert Enum.to_list(stream) == [1,2,3,4,5]
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assert Enum.to_list(Stream.take_while(1..1000, &1 <= 0)) == []
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assert Enum.to_list(Stream.take_while(1..3, &1 <= 5)) == [1,2,3]
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nats = Stream.iterate(1, &(&1 + 1))
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assert Enum.to_list(Stream.take_while(nats, &(&1 <= 5))) == [1,2,3,4,5]
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end
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test :with_index do
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stream = Stream.with_index([1,2,3])
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assert is_lazy(stream)
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assert Enum.to_list(stream) == [{1,0},{2,1},{3,2}]
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nats = Stream.iterate(1, &(&1 + 1))
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assert Stream.with_index(nats) |> Enum.take(3) == [{1,0},{2,1},{3,2}]
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end
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defp is_lazy(stream) do
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assert is_record(stream, Stream.Lazy)
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end
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end
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